1. Field of the Invention
The present invention relates to an apparatus and a method for controlling a mode change of a hybrid electric vehicle (HEV). More particularly, the present invention relates to an apparatus and a method for controlling a mode change of an HEV, by simultaneously performing coupling of an engine clutch and shifting of the transmission during a mode change from an electric vehicle (EV) mode to an HEV mode.
2. Discussion of the Related Art
Generally, a hybrid electric vehicle is driven by a fuel-powered combustion engine and a battery-powered electric motor. Hybrid electric vehicles may be provided with optimum output torque depending on how the engine and the motor are operated while the vehicles are driven by the two power sources, that is, the engine and the motor. For hybrid electric vehicles, a transmission mounted electric device (TMED)-type power train is generally used. A TMED-type power train generally incorporates an engine clutch disposed between the engine and the motor. Thus, the hybrid electric vehicle is driven in an EV mode or an HEV mode depending on engagement (connection) of the engine clutch.
In the TMED-type hybrid electric vehicle, when a driver intends to accelerate, and therefore torque demand is suddenly increased (e.g., a kick down shift is requested), in the EV mode, the hybrid electric vehicle performs a kick down shift control that shifts the transmission to a lower gear. Moreover, the hybrid electric vehicle converts operation from the HEV mode to the EV mode by coupling the engine clutch and using the power of the engine.
Due to complexities associated with transmission shifting control or engine clutch control, either a shifting operation is performed after coupling the engine clutch, or an engine clutch coupling operation is performed after shifting the transmission, according to the torque demand of the driver, when the coupling of the engine clutch and the shifting of the transmission are required simultaneously. Thus, responsiveness of the hybrid electric vehicle may deteriorate and an acceleration demand of the driver may not be satisfied when the shifting operation and the coupling operation of the engine clutch are performed sequentially.
The above information disclosed in this background section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.